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Hardiness zones for bulbs

Hardiness zones for bulbs: The numbers that always seem to go along with a plant description can be confusing. What exactly does it mean when a plant is hardy to your zone? What this is telling you is how much cold the plant can withstand without freezing to death. Climate zones are based on the average low temperatures that each area of the country has in winter. Meteorologists have arrived at this figure by averaging the temperatures over a 15 year period for each different region of the country.

The lower your zone number, the lower your average low temperature will be. Zone 5, for instance, had an average low temperature of -20°F for the years from 1974 through 1986. This doesn't mean it was always that cold - just that it was unusual for there ever to be a night colder than that. In zone 10, the average low temperature is going to be well above zero (typically it is between 30 and 40° F), meaning that it is unlikely that a plant would ever freeze to death in that zone - although weather can be unpredictable, and freezes happen even in Florida.

Using the Hardiness Zone Map

We want you to get the best results from what you select. That is why we have provided this Hardiness Zone Map. The Hardiness Zones are based on the average minimum temperatures for each zone. Many factors, such as sun, wind, snow cover or rainfall in your mini climate can also affect the minimum temperatures in your area as presented by this map.

Zone 3: -30° to -20° F

Zone 4: -20° to -10° F

Zone 5: -10° to 0° F

Zone 6: 0° to 10° F

Zone 7: 10° to 20° F

Zone 8: 20° to 30° F

Zone 9: 30° to 40° F

Zone 10: Above 40° F

Once you have determined the zone you live in you can use the chart as well as the zone listings in each of our product descriptions to determine which varieties are best for your garden. Keep in mind that the lower number indicates the most northerly area where plants will survive the winter, and the higher number is the most southerly area where they will perform consistently. For instance, if the description gives a range of zones 4-7, it means that the plant will perform well and winter over in zones 4,5,6, and 7. Many of our varieties do grow well outside the zone recommended. However, in northern areas, some varieties may have to be lifted and stored and in the south, some varieties may have to be planted in shaded cooler areas.

Sometimes you will see that a plant is hardy from “zones 3-8.” What this is telling you is that experience has shown that the plant does not do well in zones with temperatures higher than those that are normal in zone 8. This is based on experience - it doesn't take long to discover that a plant native to colder areas of the north is consistently going crisp when it spends its summers in the south. It is not based on meteorological data.